Generally, a tractor is an engineering vehicle designed to deliver a high tractive force and conduct different kinds of work in the fields of agriculture or construction. At present, tractors used in agriculture typically include a front loader provided on a front end of a tractor body, and an attachment mounted to the front loader so as to conduct various kinds of work, such as transportation, unloading, loading, etc. Furthermore, a rotavator or the like is mounted to a rear end of the tractor body by a rear link so that work such as plowing can be conducted.
In such tractors used in agriculture, power generated from an engine is classified into movement-related power which is transmitted to wheels through a transmission to enable a tractor to move, and PTO (power take-off)-related power which is used to drive different kinds of operating implements mounted to the tractor. To embody transmission of the movement-related power, a four-wheel drive system is typically used.
The conventional tractor is configured such that a body frame has a planar structure. Power of the engine is first transmitted to a rear wheel axle which is collinearly disposed with the engine. The power is thereafter transmitted to a front wheel axle after passing below the engine. Therefore, the engine must be disposed at a comparatively high position, thus raising the center of gravity of the tractor, thereby reducing the stability. Furthermore, there is no choice but to lower the installation position of the front wheel axle.
In a conventional tractor having the above-mentioned construction, the driver cab provided with the driver seat cannot be disposed above the area where the engine is located, whereby the reduction of the size of the body of the tractor is limited. Furthermore, the front wheel axle is disposed at a comparatively low position. Hence, the front wheels can be turned only to a predetermined extent in a clockwise or counterclockwise direction, because the front wheels are impeded by the front wheel axle.